I'll be the first to say that building muscle and strength is more art than science.

Sure, there are scientific principles that constitute the foundation of optimal training, but when it all boils down, effort and consistency remain the most important aspects of your long-term progression.

Still, there's something about precise, solid data based in science that appeals to us. Maybe it's our need to feel comforted in our choices, or maybe we just want to look for something certain and immovable to hold on to.

Either way, it's nice to have some clear-cut things to fall on when we're questioning our training and nutrition.

This series will give you just that in the form of precise percents that are applicable to training and nutrition. While you should take these numbers with a grain of salt (if I mention 20%, then 22% is probably fine, too), the general idea they provide is solid as steel.

0%

1 – External Load for Plyometrics

Additional loads for plyometric drills can put a lot of stress on the knee and hip joints, and these types of drills are already plenty stressful on these structures. The main objective of plyometric drills is a rapid turnover between the landing/absorption phase and the projection phase. If external loading is added, the turnover time will increase and the efficacy of the exercise will decrease.

Soviet literature indicates that during plyometric drills (e.g. the depth jump) you up the intensity by increasing the height of the drop prior to the jump, not by increasing the external load. And the height of the drop is only increased if jumping power and turnover time can be maintained.

2 – External Load for Sprinting Speed

When performing sprints to build speed, it's best to stay away from any additional loading. A decrease in sprinting speed of a mere 10% due to external loading drastically changes the running motor pattern and can make you slower, not faster.

A lot of people, and even (misinformed) coaches, recommend sprinting against a resistance by means of a weight vest, a speed chute, or weighted insoles. This is a bad idea. It generally leads to slower running speeds as the body "learns" to put more emphasis on strength and a bit less on speed during sprints.

For example, an athlete I worked with ran a 4.24 40-yard dash. He then went to a track "guru," as he wanted to become a sprinter (he was a bobsleigh athlete before). This "guru's" main method was sprinting with weighted insoles. His logic, which seems plausible in theory, was that if you can become faster with slightly heavier shoes, you'll be even faster when you remove the resistance.

The results? After five months, the athlete's 40 went up to 4.46 without any real physical changes (he wasn't overtrained, weaker, fatter, or heavier). Video analysis of his technique showed that his running stride had changed: his back leg drifted further back and took a lot more time to recoil back to the "pushing" position. The added weight lead to drastic changes in running technique, and this guy was a pretty advanced athlete with solid sprinting technique.

Now, weighted running can be used for non-sprinting athletes as a way to do energy system work. By non-sprinting athletes, I mean those who don't require perfect running technique to perform in their sports. Hockey players are the best example of this. For these guys, weighted sprinting work is acceptable as long as it's combined with regular sprints during the same session.

10%

1 – Low End for Ballistic Exercises

This is the lower end of the load range to use on ballistic exercises. Ballistic refers to movements where there's an actual projection of the source of resistance, for example jump lunges, jump squats, medicine ball throws, etc.

At a load of 10% of the maximum related lift (e.g., 10% of the max squat for jump squats, 10% of the close-grip bench press for medicine ball throws from chest, etc.) the speed-strength portion of the power spectrum is emphasized, with a great dominance placed on acceleration.

Here are some examples of ballistic exercises:

Jump lunges

Jump squats

Medicine ball throws

2 – Maximum Strength Decrease

When you're training for max strength, don't accept a drop-off of more than 10% on an exercise during the workout.

That 10% represents a decrease in performance and can be calculated either via a decrease in reps per set (unpractical when it comes to limit strength training because there aren't enough reps), in weight used, or in lifting speed (calculated by the time it takes you to complete a set under the prescribed lifting form).

For example, if you have several sets of three reps on the bench press and have a top working weight of 325 pounds, it means that it's okay to have to lower the weight as you get tired. But if you can't lift 295 pounds for three reps, then the fatigue was excessive and you should stop the exercise even if you technically have more sets to do.

You can also use lifting time, but this is only applicable for strength and power methods, not bodybuilding ones as these are often done slowly on purpose.

To use time as a guideline, have a partner time your sets. If there's an increase of 10% or more in the time it takes you to complete the set, then you should stop the exercise even if you have more sets left.

Let's say that you're training with 315 pounds for three reps on the bench press, and you complete your first set in 20 seconds. If a following set takes you more than 22 seconds, stop the exercise.

This method is only effective if the set lasts above 20 seconds, though. Less than that and the time difference is insignificant and could be simply due to technique.

This may sound complicated, but it really isn't. The bottom line is that when you're doing strength work, you should stop an exercise before you lose your strength.

3 – Maximum Load Difference During Sets

Performing sets of different weights for one exercise is becoming more and more popular. Wave loading and plateau loading are prime examples of this.

Wave loading refers to performing sets in the form of "waves." One wave normally has three sets (with rest between sets, of course), and each set of the wave is heavier than the preceding one. When the wave is completed, you start a second with a slightly heavier weight than you started the first wave with.

For example:

3/2/1 Wave

Set 1: 3 reps with 85% of max

Set 2: 2 reps with 88% of max

Set 3: 1 rep with 92% of max

Set 4: 3 reps with 88% of max

Set 5: 2 reps with 92% of max

Set 6: 1 rep with 95% of max

Plateau loading refers to doing two (or more) sets at a certain weight before moving up or down for two (or more sets). You can have double plateaus (four total sets; two sets of two different weights), triples (six total sets; two sets of three different weights), and even quads (eight total sets; two sets of four different weights).

For example:

Set 1: 6 reps with 80%

Set 2: 6 reps with 80%

Set 3: 4 reps with 85%

Set 4: 4 reps with 85%

Set 5: 2 reps with 88%

Set 6: 2 reps with 88%

In both cases, the load variance between the lighter and heavier set of the series shouldn't be more than 10%, especially when working to build strength. The reason is that a difference of greater than 10% normally leads to different motor unit recruitment patterns. This leads to various adaptive demands on the nervous system for one precise motor pattern, which translates into slower gains in that regard.

4 – The Magic Number for Abs (and Carbs)

The accepted threshold for being lean by hard training standards is 10% body fat. Also, this is the body fat percentage where you can increase the amount of carbs in your diet, even when dieting down.

20%

1 – Maximum Drop-Off for Bodybuilding

Since bodybuilding methods, contrary to strength and power methods, are often based on cumulative fatigue and metabolite accumulation, it's normal to expect a substantial loss of performance (20%) during the execution of an exercise.

It's even acceptable, too.

See, with strength and power methods, the drop-off is due to systemic neural fatigue, which we want to minimize as much as possible, as it takes time to recover from. However, with higher reps and targeted bodybuilding work, the burden on the CNS is much lower, and the main cause of the drop-off is thus metabolic or muscular fatigue, which is much easier to recover form.

Since the reps are higher, as well as the drop-off margin, we can use reps to determine the drop-off point.

For example, imagine you start doing sets of ten hard reps with 225. If you reach a point where you can't get eight good reps, you should terminate the exercise, or lower the weight by 20% and do one last set.

2 – Load to Increase Ballistic Acceleration

This is the optimal load to build acceleration by using ballistic exercises. Lighter weights, as we saw earlier, are great for building speed. But to maximize acceleration, loads of 20% of your maximum on the corresponding lift is a better choice.

3 – Percentage of Dietary Fat

Studies have shown that individuals consuming fewer than 20% of their calories from dietary fat have decreased levels of Testosterone.

This is mainly due to the fact that cholesterol is the primary raw material required to build Testosterone. If dietary cholesterol is too low, then Testosterone levels will decline.

Obviously, it's better to include plenty of good fats in that 20%. Being big isn't the only important thing; being healthy is pretty important, too!

Not to mention that good fats like omega-3 fatty acids (Flameout) improve insulin sensitivity, which means that your body will have the natural tendency to send more of the ingested nutrients to your muscles instead of your adipose collection.

30%

1 – Maximum Weight for Ballistics

If you use a training weight of more than 30% for ballistic movements, you defeat the purpose of the exercise, which is to build acceleration, velocity, and power. Not to mention that more than 30% of the corresponding lift (e.g. 30% of the back squat for jump squats) carries a greater risk of injury.

This graph from my book Theory and Application of Modern Strength and Power Methods shows that 25 to 30% is the load where you have the best gains in high-velocity power (also called speed-strength).

By the way, I established this graph by calculating the speed and power output with every load from 10 to 100% on the squat using the Tendo sports unit.

40 to 50%

1 – Volume Decrease for Deloading

Deloading is basically a planned decrease in training stress in order to allow the body's systems to recover and supercompensate from the accumulation of training (and non-training related) stress.

A lot of people often deload by lifting lighter weights. That's a mistake. Deloading is best done by lowering the volume 40 to 50% instead of the intensity (weight used). Keeping the weights up is the best way to maintain, and most often gain, strength while deloading.

Reducing intensity and keeping the volume up will work to reduce chronic fatigue and alleviate joint aches and pains. So, if you're suffering from one of those two syndromes, then you should use a load reduction instead. But if you're physically fine, all of your deloading phases should be based on lowering the volume and keeping the weights up.

A normal deloading "week" typically lasts anywhere from 5 to 10 days depending on the length of your normal training split, but a calendar week is the norm.

You can decrease volume either by decreasing reps per set or the number of sets per exercise.

Option #1: Decreasing the number of reps

This is best done if you're performing sets of at least three reps. It simply consists of keeping the same training weight, but lowering the number of reps you're doing on each set.

If your previous week on the bench looked like this:

3 sets of 315 x 6

2 sets of 325 x 4

You'd do the following:

3 sets of 315 x 4

2 sets of 325 x 2

Don't increase the weight! The sets should feel easy; that's the goal of a deload.

Option #2: Decreasing the number of sets

You can also keep the same number of reps per set, but decrease the total number of sets.

In the preceding example, you'd switch to something like this:

2 sets of 315 x 6

1 set of 325 x 4

Not exactly 40% in either case, but it's close enough.

As for when to deload, deloading is best done when you're on the verge of excessive fatigue. If you deload when you don't need it, you won't get any benefit from it. It can be used as a preventive measure when used on a frequent basis, but if it's used before you've created enough cumulative fatigue, then you might actually find yourself regressing during the deloading week.

So, the frequency will depend on how hard you're training, how much external stress you're under, your nutritional status, etc.

I personally like to use my waking heart rate as a way of deciding when to deload. After a few days of rest, take your resting heart rate upon waking. Take it for a full 60 seconds, not 15 seconds and then multiply because this increases the margin of error. Ultimately, if you have access, use a heart rate monitor.

This is your baseline value. Take your resting heart rate every morning from that point on. If your value is elevated by more than seven beats per minute for more than two consecutive days, you're probably due for a deloading week.

You can also go by psychological factors. Total lack of motivation, moodiness, lack of patience, no "toughness" during your workouts, etc. are all signs that you should deload.

Finally, lingering joint pains are also a sign that you should back off. But in this instance, you might consider backing off the amount of weight you're lifting instead of just the volume.

2 – Low End for Speed Work

Also known as the Westside speed method, 40 to 50% is the low end of the loading range for speed work on traditional strength exercises.

Looking back at the previous velocity and power graph, you'll notice that if the optimal mix of velocity and power (speed-strength) occurs between 25 and 30% (ballistic exercises) that the peak power output itself is shown in the 40 to 50% range.

So, when performing speed work on traditional exercises like the bench press and squat for maximum power development, you should pick a load that's within that range.

3 – Protein Percentage for Muscle

While I normally prefer to use grams per pound to build a diet (e.g. 1.5 grams of protein per pound of bodyweight), most of the diets I design always come up to a protein intake of 40% of the total caloric intake.

I find this to be true both for muscle gain and fat loss diets, although the percentage tends to be a bit higher during fat loss phases than growth spurts.

A lot of muscleheads actually go too heavy on the protein compared to other nutrients. This is problematic while losing fat, but not so while gaining muscle.

The reason is as follows: If one macronutrient is disproportionately high, the body will adapt to use this as its main fuel source. So, if your protein intake is way higher than your other nutrients, your body will become good at using protein for fuel. Since protein is an inefficient fuel source, the body will be quick to breakdown muscle tissue to produce the energy required. You'll be burning down the walls to heat the house!

So, even when dieting down, roughly 50 to 60% of your food intake should be in the form of the main energetic nutrients (carbs and fat). The proportion of each will obviously vary depending on the type of diet you're following, but 40% protein to 60% fat/carbs is a good proportion to shoot for to optimize body composition.